Fabrication of γ-Al₂O₃ Nanoarrays on Aluminum Foam Assisted by Hydroxide for Monolith Catalysts

Heat distribution and good adhesion of the washcoat on monolith catalysts are critical to improving catalytic activity and long-term stability. Compared with cordierite, metal foam presents a high thermal conductivity coefficient. Also, the availability of "washcoat" in situ grown on metal substrates opens the door to eliminating the problem of coating peeling. Generally, hydrothermal or thermal methods are used for the fabrication of in situ grown washcoat on metal substrates. In this research, the aluminum foam monolith vertically aligned Al₂O₃ nanowire array is successfully prepared at ambient temperature in an alkaline solution for the first time. Furthermore, the Pt-loaded Al₂O₃ nanowire array (0.5 g_Pt/L _monolith) is applied to C₂H₄ degradation. The catalyst converts 90% C₂H₄ at 147 °C with a gas hourly space velocity (GHSV) of 20,000 h^-1. And a little decrease (1%) is observed in catalytic activity, even in 15 vol % water vapors. The catalysts show good thermal stability and water resistance property over 36 h at 300 °C. Above all, this study presents a simple way of in situ growth of washcoat on metal-substrate monolith with potentially scaled manufacturing. And the monolith catalyst shows good catalytic performance on C₂H₄, which can be applied for volatile organic compound treatment.